Invertebrate Pollinators Research Articles

A rapid and accurate visual assessment of nectar production can reveal patterns of temporal variation in Banksia ericifolia (Proteaceae)

Banksia species are conspicuous in Australian heathlands and woodlands and provide a major source of nectar for a range of vertebrate and invertebrate pollinators. However, nectar production by Banksia is difficult to measure because inflorescences comprise large numbers (hundreds to thousands) of tiny flowers. Our aim was to quantify variation in nectar volume among B. ericifolia L.f. plants, but existing techniques were too time consuming or required destructive sampling of inflorescences. We estimated nectar volume by counting the number and estimating the size of nectar drops on a sample of flowers on each inflorescence. Our technique was fast (10 min per inflorescence) and a highly significant positive relationship was found between visual estimations and direct measures (capillary tubes and micropipettes) of nectar volume (r = 0.92; P ≤ 0.0001). This technique thus provides an alternative to current techniques for measuring nectar volume in plants that have large numbers of small flowers arranged in dense inflorescences. By using this technique, we found significant variation among days in nectar volume produced by each of five B. ericifolia plants (P ≤ 0.02). Furthermore, days of high and low nectar production were synchronised among plants. We concluded that the temporal variation found may be the result of fluctuations in environmental variables, rather than the age of an inflorescence. Indeed, nectar volume was found to be significantly correlated with a range of weather variables including daily maximum temperature (°C), precipitation (mm), wind speed (km h–1) and relative humidity (%). However, larger-scale and longer-term studies are needed to adequately examine any relationship between environmental variables and nectar production.

Causes and Extent of Declines among Native North American Invertebrate Pollinators: Detection, Evidence, and Consequences

Cane, J. H. and V. J. Tepedino 2001. Causes and Extent of Declines among Native North American Invertebrate Pollinators: Detection, Evidence, and Consequences. Conservation Ecology 5(1):1. https://doi.org/10.5751/ES-00252-050101

Paleobotanical and biogeographic history of the legumes (Leguminosae), an important component in Cenozoic and modern tropical terrestrial ecosystems

The Leguminosae are consistently one of the two or three most important angiosperm families in diversity and abundance in modern African and American tropical and subtropical lowland ecosystems. Many legumes are colonizers of disturbed sites while others are components of more mature communities. The great diversity and abundance of legumes reflects characteristics that have made them important components of tropical ecosystems. One of the most significant of these is the ability of most legume species to enrich the soil through the activities of bacteria in their root nodules. Legumes are also important as sources of food to vertebrate and invertebrate pollinators alike. Legumes have well known plant-pollinator relationships with bats, birds, hymenoptera, and lepidoptera and their diversity is sometimes linked with their strong association with specialized animal pollinators. Legumes also enjoy a variety of unusual defense strategies based on various interrelationships with ants. Thus, the evolution of specialized interrelationships with a diversity of organisms has helped the legumes become a family of considerable importance in American and African tropical ecosystems.Legumes are well represented in the fossil record and the paleobotanical data now available demonstrate that the family was an important component in tropical ecosystems by the Paleocene/Eocene. Sediments of the Mississippi Embayment in southeastern North America are yielding the most abundant and diverse assemblage of fossil legumes. The individual legume taxa in this specific subtropical to tropical flora represent a wide variety of different biogeographic distribution patterns. Legume fossils that are most closely related to extant taxa that occur only in tropical South America today are the most common components of this assemblage. Other biogeographic distribution patterns include American-Asian disjuncts, Asian, African, and Pantropical taxa. Although several of the fossil taxa are widespread in the North American Tertiary, these cases are restricted to taxa that have an Old World Tropics or American-Asian disjunct distribution today. The South American taxa seem to have been largely restricted to the Mississippi Embayment system.The Paleocene/Eocene legume fossil flora suggests that nitrogen fixation and highly specific insect pollination mechanisms were well established by that time. In addition, bat pollination in legumes may have been established by the upper Eocene. Specialized foliar glands, which are indicative of defense strategies involving ants, are present by at least the Oligocene. Although fruit and seed dispersal in legumes is largely abiotic, a wide variety of fruiting structures and abiotic dispersal mechanisms occur in the family and many of these were present by the Eocene.This study of the fossil record of the Leguminosae is demonstrating that the legumes were well established and diverse by the Paleocene/Eocene and that many of the functions and relationships that make them important in modern tropical ecosystems were established by that time.

Biotic pollination mechanisms in the Australian flora — a review

Abstract Various aspects of pollination biology in Australia are examined and the relevant literature is reviewed in detail. The history of Australian pollination studies is briefly discussed and particular emphasis given to the contributions made by some of the more outstanding workers in this field. The enormous diversity of the pollen-vector fauna is documented and emphasis given to the adaptations of particular vector types and of the blossoms that they visit. The pollination role of the Australian invertebrate fauna is discussed and an assessment made of the proportion of anthophilous (i.e., flower-frequenting) taxa in various insect groups. Critical examination of recorded feeding habits of the Australian coleopteran and dipteran faunas reveals that at least 28 of the 121 coleopteran families (i.e., 23%) and 44 of the 87 dipteran families (i.e., 51%) contain anthophilous species. The Australian bee fauna, consisting of c. 3000 species, is exclusively anthophilous and constitutes the most important group of invertebrate pollinators; a comprehensive table listing those bee taxa that have been recorded visiting the blossoms of native plant genera, is provided. Two vertebrate pollination systems are important in the Australian context: ornithophily, involving flower-visiting birds as the pollen vectors, and therophily whereby flying or non-flying mammals act as the pollen transporters. Mammal pollination (therophily) is discussed at length, and several new terms introduced to describe the syndromes of marsupial (metatherophily), placental (eutherophily), and rodent (sminthophily) pollination respectively; comprehensive tables listing the anthophilous chiropteran and marsupial taxa of Australia are also provided. The role of various types of pollen vectors in promoting convergent and divergent floral evolution in the Australian flora is illustrated with examples from selected plant taxa. New information on the pollination biology of the tribe Boronieae (Rutaceae) is presented, and some of the more unusual floral adaptations noted. The review concludes by emphasising those areas where future research is needed and where broad co-operative studies would be most productive.